Issued  September  16,  1911. 


U.S.  DEPARTMENT   OF  AGRICULTURE, 

BUREAD   OF   ENTOMOLOGY— CIRCULAR   No.  142. 

L.  O.  HOWARD.  Enlomologial  and  Chief  ol  Bureau. 


THE  [NDIAN-MEAL  MOTH 

AND 

"WEEVIL-OUT"  PEANUTS. 


C.  IT.  POPENOE, 

Entomi  *  r<>i>  and  Stored  Product  Insect  Tnvestig 


•    Mi;     11 


WASHINGTON   :  GOVERNMENT   PRINTINO  OFFICE   :  1911 


BUREAU  OF  ENTOMOLOGY. 

L.  O.  Howard.  Entomologist  and  Chief  of  Bureau. 

C.  \j.  Marlatt,  Entomologist  and  Acting  Chief  in  Absence  of  chief. 

R.  S.  Clifton.  Executive    Assistant. 

W.  F.  Tastet.  Chief  Clerk. 

F.  H.  Chittenden,  in  charge  of  truck  crop  and  stored  product  insect  investi- 
gations. 
A.  D.  Hopkins,  in  charge  of  forest  insect  investigations. 
W.  D.  Hunter,  in  charge  of  southern  field  crop  insect  investigations. 
F.  M.  Webster,  in  charge  of  cereal  and  forage  insect  investigations. 
A.  L.  Quaintanci  .  in  elm rge  of  deciduous  fruit  insect  investigations. 
E.  F.  Phillips,  in  charge  of  bee  culture. 

D.  M.  Rogers,  in  charge  of  preventing  spread  of  moths,  field  work. 
Rolla  P.  Currie.  in  charge  of  editorial  work. 
Mabel  Colcobd,  in  charge  of  library. 

Truck  Crop  and  Stored  Product  Insect  Investigations. 

F.  IT.  Chittenden,  in  charge. 

H.  M.  Russell,  C.  II.  Popenoe,  Wm.  B.  Parker,  H.  O.  Mabsh,  Tikis.  II.  .Tones, 

M.  M.  High,  Fred  A.  Johnston,  entomological  assistants. 
I.  J.  Condit,  collaborator  in  California. 
P.  T.  Cole,  collaborator  in   tidewater  Virginia. 
W.   N.  Ord,  collaborator  in   Oregon. 
Marion  T.  Van  Horn,  preparator. 


Circular  No.  142. 

United  States  Department  of  Agriculture, 

BUREAU  OF  ENTOMOLOGY. 
L.  O.   HOWARD,   Entomologist  and  Chief  of  Bureau. 


THE  [NDIAN-MEAL  MoTII  AND  "WEEVIL-CUT"  PEANUTS. 

Bj    C.   II.    Popi  \"- , 
Entomological    {.ssistont,  Truck  Crop  and  Stored  Product  Insect  Investigations. 

Until  a  few  years  ago  the  peanut  had  been  considered  as  almost 
immune  from  insecl  injury,  the  plant  being  affected  by  few  in 
and  the  "nuts"  being  protected  by  their  thick  shells  against  most 
of  the  usual  bisect  enemies  of  stored  products.  There  are.  it  is 
true,  one  or  two  species  of  beetles  which  by  reason  of  their  horny 
jaws  are  able  t<>  cut  readily  through  the  woody  tissue,  but  the  injury 
from  any  of  these  had  b<  en  infinitesimal. 

Since  the  advent  of  the  mechanical  thrasher  or  "peanut  picker" 
conditions  have  changed  to  a  great  degree.  The  machinery  is  by 
no  mean-  perfect  as  yet,  and  the  tendency  of  the  operator  to  feed 
the  peanuts  too  quickly  through  the  machine  results  in  a  large  p<  r- 
centage  of  broken  shells,  and  affords  easy  entrance  to  several  of  the 
common  stored-product  pests.  It  is  estimated  that  between  20  and 
30  per  cent  <>l'  the  peanuts  are  injured  in  this  manner,  consequently 
becoming  "seconds,'1  and  in  nearly  every  case  becoming  infested  in 
a  short  time  a  fter  being  stored. 

Another  source  of  injury  to  the  shells  of  the  peanuts,  affording 
ingress  to  insects,  is  the  practice  of  piling  the   -ached  nuts  high  in 

lA1    a    ii ting   held   June    14,    1911,   at    the    Department  of  Agriculture,    Washington, 

D  which    was   atl  many    prominent    peanut    dealers,    chiefly    from    Norfolk, 

Suffolk,  and   Portsmouth,   Va.,  and  from   North  and  Smith  Carolina,  the  question  <>f  how 

.i  "  peanuts  was  discussed  hy  Mr.   P  writer,  and  an 

menl  waa  reached  t<>  undertake  the  project  of  testing  remedies  tor  peanuts  In  store.     The 

value   of   the   peanut    Industry   for    1910   was   estimated   at    $15,000, Assumu 

Injury   to  .    the   loss   to   the 

peanut  |  ve  estima  0,( One 

prominent  dealei  Injury,     in  t  i  *  !•  -  - 

■.hen-  a  preliminary  Investigation  was  made,  Mr.  Popenoe  was  assisted  bj 
Mr    r.    \    Johnston  and  bj   Mr    W.  i:    Beat  tie,  "t  the  Bureau  "i    Plant   Industry.     I 
ii  was  owing  to  the  servl       ol  Mr    Beattle  thai  this  investigation  was  begun.     The  i 
panying  circular  is  being  Issued  !>y  request  of  the  peanut  !■'.  if.  Chittenden. 


INDIAN-MEAL    MOTH    AND        WEEVIL-CUT        PEANUTS. 


the  .storage  warehouses.  This  makes  it  necessary  for  the  workmen 
to  climb  upon  the  stacks  of  sacked  peanut-,  thus  breaking  many 
more,  and  increasing  the  percentage  of  infestation. 

The  insect  chiefty  concerned  in  the  injury  to  stored  peanuts  is  the 
larva  of  a  small  dusky  moth,  commonly  called  the  Indian-meal  moth 
(Plodia  interpunctella  Hbn.),  a  common  and  well-known  pest,  habit- 
ually frequenting  all  places  where  foodstuffs  and  cereals  may  be 
stored,  and  feeding,  as  its  name  would  indicate,  upon  meal,  flour. 
and  grain.  It  also  attacks  dried  fruits,  nuts,  chocolate,  and  seeds. 
Like  other  related  species,  it  prefers  darkness  or  semidarkness, 
although  at  times  seen  abundantly  in  well-lighted  storerooms.1 

DESCRIPTION    OF    STAGES. 

The  adult  or  moth,  shown  in  the  accompanying  illustration 
(fig.  1,  a),  is  about  one-half  to  three-fourths  <d'  an  inch  in  expanse 

of  wings.  The  outer  two- 
thirds  of  the  forewing  is  of  a 
reddish  brown  color  with  a 
coppeiy  luster,  while  the  in- 
ner third  is  whitish  gray,  giv- 
ing the  insect,  while  resting, 
the  appearance  of  being 
cloaked.  The  hind  wines  are 
dusky  gray.  The  larva, 
shown  at  c,  d,  and  e.  in  the 
figure,  is  dirty  whitish,  vary- 
ing at  times  from  greenish  to 
a  decided  pink  cast.  It  is 
about  one-half  of  an  inch  in 
length  when  mature.  The  pupa,  shown  at  h,  is  about  three-eighths  of 
an  inch  in  length  and  light  brown  in  color.  It  is  inclosed  in  a 
cylindrical  silken  cocoon  or  web,  which  may  be  mixed  with  frass. 
The  eggs  are  small  and  white,  and  arc  deposited  upon  the  food  sub- 
stance selected,  either  singly  or  in  groups  of  three  to  a   dozen. 

LIFE  HISTORY   AM)  HABITS. 

The  moths  usually  make  their  appearance  in  numbers,  in  Virginia, 

by  about  the  middle  of  June,  and  may  be  seen  flying  in  the  darker 
portions  of  the  storage  houses  or  resting  upon  the  sack-  of  peanut-. 

'In  addition  to  the  Indian-meal  moth,  several  other  inserts  are  frequently  found  to 
Injure  peanuts  in  storage,  These,  in  the  order  of  their  Importance,  are  as  f..!iows:  The 
rust-red  Hour  beetle  [THbolium  naialc  Fab.),  the  saw-toothed  grain  beetle  (Silvanus 
8urinamensi8    L.),    the    cadelle    (Tenebroides    mauritanicus    L.),    the    ti^   moth    (Ephestid 

runt,  II, i    Walk.),    and    the    Mediterranean    Hour    moth     (Ephestia    kuehniella    Zell.).        The 

three  former  species  are  capable  of  cutting  through  the  shells  of  peanuts,  but  rarely 
occur  in  such  numbers  as  t"  !»■  injurious  to  them.  They  are  amenable  to  the  rem. 'dies 
mentioned  In  this  publication. 


Pig.  1. — The  Indian-meal  moth  (Plodia  inter- 
punciella)  :  a,  Moth;  b,  chrysalis;  c,  cater 
pillar:  d,  head:  (,  first  abdominal  segment 
of  caterpillar,  more  enlarged.  (From  Chit- 
tenden i 


[NDIAN-MEAL    MOTH     \M>   "  w  NTUTS.  6 

Id  unheated  houses  the  first  eggs  are  laid  in  March  and  April  by 
the  moths  just  issuing  from  the  pupal  stage.  At  this  time  they  are 
comparatively   scarce   and   are   littli  inter,    when   the 

sive  generations  have  been  allowed  to  multiply,  they  become 
very  abundant,  reaching  their  maximum  in  the  Latter  pari  of  Au- 
gust. In  heated  rooms  reproduction  may  be  continued  throughout 
the  winter. 

Tin   eggs   hatch  in  about    I  da  r  deposition,  and  the  larvae 

at  once  begin  the  work  of  destruction.     The  larvi  con- 

sidered to  Last  about  L8  days,  varying  according  to  weather  condi- 
tions. During  this  time  the  larva1  crawl  from  one  kernel  to  another, 
feeding  as  the}  goj  and  spinning  a  quantity  of  silken  thread,  which, 
mixed  with  food  particles  and  excrement,  disfigures  and  injures  the 
material  over  which  they  craw  1.  When  the  nuts  have  been  attacked  for 
some  time  the  entire  mass  re  >  a  mat  of  webbing  mixed  with 

powdered  food  material  and  I'm--.  When  fully  mature  the  larvae 
crawl  about,  seeking  a  place  for  puliation  and  spinning  large  quan- 
tities of  web  as  the]  go,  finally  making,  in  cracks  in  tin  flooring, 
between  bags,  or  in  other  dart  places,  cylindrical  silken  cocoons,  in 
which  the  larvae  transform  to  the  pupal  stage.  In  hibernation  the 
larva  remains  throughout  the  winter  in  the  cocoon,  in  a  state  of 
quiescence,  pupating  early  the  following  spring. 

The  pupal  stage  usually  lasts  from  5  to  LO  days  before  the  issuance 
oi'  the  mature  insect,  making  the  life  cycle,  under  good  conditions  of 
temperature,  from  1  to  5  weeks  and  affording  opportunity  for  from 
A  to  7  broods  or  generations  oi   larvae  in  one  year.     A  -male 

is  capable  of  depositing  from  300  lo  400  eggs,  it  may  be  seen  that 
the  capacity  for  injury  is  c<  nsiderab 

\  \  ll  l;  u.   I  \l  ■  M  II  -. 

This  in-eet  has  a  number  of  natural  enemies,  the  mosl  prominent 
being  two  hymenopterous   parasites.  Omorgus  frumentarhiii   Rond. 
ami  Uadrobracon  hebetor  A  dim.    These  two  form-  do  much  to  • 
the  multiplication  of  this  and  other  similar  pests. 

II   V]  EDIA]     Ml   \-l   R]  S. 

Although  at  first  sight  this  insect  seems  to  presenl  a  problem  to  the 
r.  its  control  i-  by  no  mean-  so  difficult  as  might  be  sup]  i 
At    leasl    two  effective   method-   of  control   arc  applicable,   namely, 
heal  and  fumigation. 

7  In  h<  <ii  method  of  control.  The  treatment  by  heat,  while  new  in 
it-  application  to  cut  ire  buildings,  has  during  the  past  two  years  been 

description  of  stages  and  notes  on  I    ■  e  are  complied  largely  from  thi 

of  Dr.  V.  II.  Chittenden,  published  In  Bull  «,  of  the  Burea  oology, 

i  I  Stati     i  leparl  men!  •  ■'    Igrlcul 


4  INDIAN-MEAL   MOTH    AND    "  WEEVIL-CUT"    PEANUTS. 

used  very  successfully,  both  in  the  control  of  the  Indian-meal  moth 
and  in  that  of  the  related  Mediterranean  flour  moth.  Both  Prof. 
G.  A.  Dean,  of  the  Kansas  Agricultural  Experiment  Station,  and  the 
author  have  used  this  method  in  the  control  of  the  flour  moth,  and  it 
was  used  quite  successfully  by  the  latter  in  a  peanut  mill  in  Virginia. 
It  is.  of  course,  only  applicable  to  mills  heated  by  steam.  In  the 
proper  application  of  this  method  the  mill  should  lie  thoroughly 
piped  and  furnished  with  suitable  radiators.  Sufficient  radiator  sur- 
face should  be  supplied  to  obtain  a  temperature  of  120°  to  125°  F. 
A  few  courses  of  1^-ineh  pipe  placed  along  the  side  walls  should 
easily  bring  about  the  desired  results.  If  a  warm  day  in  the  summer 
is  selected  and  the  steam  is  employed  at  a  pressure  of  75  to  100 
pounds,  only  a  small  amount  of  radiator  surface  is  needed.  To 
permit  the  most  effective  penetration  of  the  heat,  the  bags  of  nuts 
should  be  piled  only  a  few  feet  deep,  as  experience  has  shown  that 
some  time  is  required  for  the  peanuts  within  the  piles  to  be  raised  to 
a  uniform  high  temperature.  The  building  should  be  closed  tightly 
and  the  temperature  raised  to  120°  F.,  remaining  at  this  point  for  at 
least  G  hours.  A  longer  time  is  advisable,  as  the  penetration  is 
thereby  increased.  Bags  of  shelled  stock  are  with  difficulty  heated  to 
the  center  without  a  long  exposure,  and  although  the  larvae  work 
near  the  outside  of  the  bags  they  may  crawl  to  the  center  to  escape 
the  great  heat,  which  tends  to  make  them  much  more  active. 

The  temperature  should  not  be  raised  a  hove  125°  F.  in  the  case  of 
peanuts,  as  experiments  have  shown  that  a  slight  degree  of  blanching, 
or  slipping  of  the  "  skin,"  takes  place  in  shelled  Spanish  nuts  exposed 
to  such  a  heat.  Virginia  peanuts,  being  much  le>s  oily,  are  not 
affected,  while  no  injury  whatever  takes  place  in  the  case  of  unshelled 
nuts.  Germination  is  likewise  unaffected,  peanuts  exposed  ('.  hours 
to  a  temperature  of  140°  germinating  better  and  more  quickly  than 
those  indicated.  A  temperature  of  116°  is  fatal  to  insect  lii'e  in  a 
short  time,  larvae,  pupae,  and  adults  of  the  Indian-meal  moth  dying 
in  less  than  one-half  hour,  when  exposed. 

Fumigation. — In  mid.-  and  storehouses  where  the  beat  method  is 
inapplicable,  it  may  be  necessary  to  fumigate  with  hydrocyanic-acid 
gas.  On  dt< en nl  of  the  extremely  poisonous  naturt  of  this  gas  >  are 
IS  in  <  i  ssary  in  its  use,  and.  where  careless  Or  ignorant  help  is  em- 
ployed, some  danger  might  accrue  through  improper  or  careless 
handling.  Before  the  gas  is  applied  the  building  should  be  tightly 
closed;  afterwards  jars  containing  the  requisite  amount  of  diluted 
sulphuric  acid  should  be  placed  therein,  and  the  paper  bags  contain- 
ing the  cyanid  of  potassium  dropped  into  these  jars,  thus  liberating 
the  gas  iu  the  room.  This  gas  is  used  extensively  as  a  remedy  for 
flour-mill   and    household    insect-,  and    where   intelligently   handled 


[NDIAN-MEAJ     MOTH     \.\  l>    "  W  I  i.\  1 1 .  (  i    I         PEANUTS.  .1 

gives  excellent  results.  Full  directions  for  its  use  are  given  in  Cir- 
cular 1 1-  of  this  bureau.3 

Carbon  bisulphid  is  also  applicable  as  a  fumigant,  and  is  highly 
effective,  although  its  great  inflammability  and  the  possibility  of  its 
explosion  when  ignited  are  ii  isure  against  its  use. 

MEANS    OF    IMU  .  ENTK  'N     '■■'■      I  111     P  ICKEB. 

In  order  to  decrease  the  liability  of  peanuts  to  insect  injury,  the 
factory   should  be  kepi  as   free  as  po  from  an  accumulation  of 

moths  during  the  summer  season.    To  this  end,  all  cai  fested 

peanuts  coming  into  the  facto  tild  be  fumig      d  before  ent  ranee. 

The  factories  should  be  30  constructed  as  to  furnish  as  few  hiding 
places  for  the  larvae  and  pupae  as  |  .     A  modern  reenforced 

concreti  structure  >>  ith  concrete  floors  may  lie.  with  proper  attention. 
kepi  almost  entirely  free  from  the  p< 

The  writer  has  seen  large  uumbers  of  the  larvae  hibernating 
tween  the  two  layers  of  a  double  floor  that   was  apparently  tight, 
and  with  ease  resisting  ordinary  efforts  to  diminish  their  numbers. 
All  cracks  and  ci  innies  large  enough  to  hold  a  small  quantity  of 
dust  may  also  prove  breeding  places  for  the  larvae. 

Care  in  attending  to  the  freedom  of  outgoing  freight  cars  from 
larvae  will  also  he  of  value  in  controlling  the  injury  due  to  insects. 
An  ordinary  freighl  car  can  be  easily  and  safely  fumigated  at  a 

not  to  exceed  $1,  with  cither  hydrocyanic-acid  gas  or  carl bisulphid. 

Even  a  thorough  cleaning  of  the  car  before  reloading  will  he  of 
value  in  dot  roving  many  insects  brought  in  with  the  previous  ship- 
ment.2 

The  storage  rooms  should  he  light  and  airy,  and  the  peanuts 
should  not  he  piled  so  high  that  it  i>  necessary  to  climb  about  on  the 
bags  in  older  to  reach  the  top  of  the  pile-.  'While  some  degree  of 
immunity  may  be  reached  by  the  storage  of  peanuts  in  large  hulk. 
still  the  incre  imount  of  breakage  from  this  method  more  than 

balances  tl  fleets  of  the  hulk  storage. 

The  storage  of  peanuts  in  elevator  bins  holding  several  thousand 
bushels  each  does  not  meet  with  this  objection,  as  in  such  case  the 
inn-  ire  trampled  hut  little,  ami  the  injury  by  insects  i-  limited  al- 
most entirely  to  the  t<.p  layer,  rarely  extending  more  than  a  foe!  or 
two  helow  ii,,-  surfai  e. 

Ml   ISURES    "l     PREVENTION     BY    THE    GROWER. 

[nfestation  of  peanuts  by  the  Indian-meal  moth  frequently  t 
place  in  the  storage  sheds  or  ham-  of  the  farmer  or  grower,  where 

'Circular  112,  Bureau  ol   Enl  -  I  States  Department  of  Agriculture. 

'Care  should  be  taken  that  railroad  agents  deliver  for  peanut  shipment  only  clean  cars. 


UNIVERSITY  OF  FLORIDA 


6  DIAN-MEAL   MOTH    AND    "  WEEVIj 


3  1262  09216  5686 


the  nuts  are  held  in  reserve  -and  only  sold  as  needed.  Where  the  nuts 
are  held  over  the  summer,  the  moths  are  allowed  to  breed  freely,  with 
the  result  that  many  nuts  that  would  otherwise  escape  infestation 
are  ruined.  Storage  in  dark,  dusty  lofts  or  sheds  also  allows  greater 
increase  of  the  insects  by  providing  a  suitable  breeding  place.  Nuts 
which  have  been  held  for  several  years  by  growers  frequently  show 
large  numbers  of  infested  kernels.  It  is  urged  in  this  connection  that 
unless  in  exceptionally  good  condition  with  regard  to  broken  shells. 
no  nuts  should  be  held  in  the  granary  of  the  farmer  later  than  the 
it  of  June,  at  which  time  the  injury  by  the  first  generation  or 
"brood"  i-  just  beginning.  When  held  later,  without  proper  fumi- 
gation and  attention,  the  multiplication  of  the  pest  is  unchecked,  with 
the  result  that  the  grade  of  the  nuts  is  materially  reduced. 

Of  primary  importance  is  the  proper  selection  and  operation  of 
the  peanut  picker  or  thrasher.  There  are  several  types  of  this  ma- 
chine on  the  market,  which  with  careful  use  may  he  depended  upon 
to  break  a  minimum  amount  of  the  shells.  The  almost  universal 
cause  of  such  injury  is  the  practice  of  crowding  the  machines  in 
order  to  thrash  a  larger  quantity  of  nuts  in  a  short  space  of  time. 
This  practice  is  reprehensible,  as  it  is  responsible  for  the  large  amount 
of  broken  peanut  shells  found  in  machine-picked  nuts.  While  more 
profitable  to  the  thrasher,  its  expediency  seems  doubtful,  as  the  grade 
of  the  tints  is  thereby  reduced  and  the  opportunity  for  infestation 
increased,  thus  reducing  the  price  obtained  for  the  product.  The  pea- 
nut packer  will  readily  pay  a  higher  price  for  an  article  in  which  he 
can  be  assured  of  a  maximum  number  of  fancy  nuts.  It  is  therefore 
suggested  that  proper  attention  be  paid  to  the  operation  of  the  picker, 
and  that  care  be  taken  that  the  machine  is  not  crowded.  This  will 
result  in  much  less  breakage  and  so  diminish  the  infestation  that 
there  will  be  little  need  of  further  precaution  in  the  matter  of  storage. 

o 


